1. Field
One embodiment of the invention relates to an optical disc such as a DVD which serves as a medium to store digitized video and audio works such as movies and music. It further relates to an optical disc apparatus which reads information recorded on the optical disc, and a digital work publication using the optical disc as a recording medium.
2. Description of the Related Art
<Outline of the DVD Standard>
One known type of optical disc for storing digital images is a Digital Versatile Disc (DVD), which has been widely used all over the world mainly in storing and delivering movie content (digital work publications). This DVD is a format created by the DVD Forum, which is open to the public as DVD Book (refer to the World Wide Web: dvdforum.org). The DVD has also been determined in international standards and JIS. Here, the international standard ISO/IEC 16448 for 120 mm DVD-ROM, one of the DVD physical formats, will be briefly explained. Moreover, there is ECMA-267 as a document associated with the international standards.
There are four types of 120 mm DVD-ROM: single-sided single layer, single-sided dual layer, double-sided single layer, and double-sided dual layer. In delivery of an accumulation of content of movies and the like, two types of single-sided discs are mainly used: one is a single-sided single layer DVD disc (4.7 GB) and the other is a single-sided dual layer DVD disc (8.54 GB). However, recently, the single-sided dual layer DVD disc has accounted for 60% of the total.
On the other hand, the development of a disc whose capacity is larger than that of the aforementioned DVD (referred to as the existing DVD) has been desired. This comes from a desire to store High Definition (HD) images into a single disc (temporarily referred to as a next-generation DVD).